I had no mystery that has rocked the world honey bees millions of bees simply dying or just disappearing leaving no -- high and snow honey. And it's -- that experts say it's getting worse and could mean shortages of honey and lots of other popular foods that we eat here's ABC's Devin Dwyer. For 63 years Charles Smith's hives have been buzzing with millions of -- They do these things -- sounds as it is hard work. But you gotta love it booming business renting -- bees to pollinate fields of blueberries and apples but then last winter many of his swarms suddenly went silence. The bees gone without a Trace Milos almost 50%. Up in this area. These are all just don't want Amin. Does what it's like to -- can't find a way back home it's a mystery that's -- beekeepers everywhere even spurring talk of a B apocalypse. A stunning one in three US bee colonies disappeared last winter with no clear explanation of why. Scientists say another big loss this year could devastate the American food supply. Fewer fees mean fewer holiday heirs to help plants produce their fruit that could mean shortages of food like broccoli celery even. Avocados. And about one in every third bite can we eat all the fruits nuts and vegetables -- really kind of enrich our diet. Those are the things that are at risk Jeff pettis is the government's top B researcher he says the disappearance of bees is getting worse -- how -- -- -- -- It's reasonable it's not great. -- USDA research lab pettis is found plenty of clues from pesticides and blood sucking mites to viruses and disease but no smoking gun. What can each of us due to be more be friendly and and maybe help this from. Plant native vegetation near whatever that area is a simple step that could help take the -- Out of a -- mystery Devin Dwyer ABC news belts -- Maryland. This is happening it's widespread tapping. -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- And a -- you can walk through a field and see them all over the floor and no where they've been northern Ghana where they drop dead. And they don't drop dead in a parking lot so they kind of fly away never come back and they're kind of never seen are really heard of again. It's affecting it can affect every aspect of the things that we eat -- -- really scary for us big time --

This transcript has been automatically generated and may not be 100% accurate.

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